Theoretically, the dose of protamine sulfate should be halved when one half-life has elapsed since the last LMW heparin dose. The longer half-life of LMW heparins (approximately twice that of UF heparin) should also be borne in mind when estimating the dose of protamine sulfate required in relation to the time which has elapsed since the last heparin dose. The anti-Xa activity of LMW heparins may not be completely reversible with protamine sulfate and may persist for up to 24 hours after administration. Neutralisation of low molecular weight (LMW) heparins:Ī dose of 1mg per 100 units is usually recommended but the manufacturer's own guidelines should be consulted. Further doses may be needed because protamine is cleared from the blood more rapidly than heparin. Patients should be carefully monitored using either the activated partial thromboplastin time or the activated clotting time, carried out 5-15 minutes after protamine sulfate administration. In the reversal of UF heparin following cardiopulmonary bypass, either a standard dose of protamine may be given, as above, or the dose may be titrated according to the activated clotting time. If heparin was administered subcutaneously, 1mg protamine sulfate should be given per 100 units of mucous heparin - 25-50mg by slow intravenous injection and the balance by intravenous infusion over 8-16 hours.

If the patient is receiving an intravenous infusion of heparin, the infusion should be stopped and 25-50mg of protamine sulfate given by slow intravenous injection. If two hours or more have elapsed, 0.25-0.375mg per 100 units of mucous heparin should be administered. The dose of protamine sulfate should be reduced if more than 15 minutes have elapsed since intravenous injection.įor example, if 30-60 minutes have elapsed since heparin was injected intravenously, 0.5-0.75mg protamine sulfate per 100 units of mucous heparin is recommended. Neutralisation of unfractionated (UF) heparins:ġmg of protamine sulfate will usually neutralise at least 100 international units of mucous heparin or 80 units of lung heparin. In gross excess, protamine itself acts as an anticoagulant.

Ideally, the dose required to neutralise the action of heparin should be guided by blood coagulation studies or calculated from a protamine neutralisation test. The dose is dependent on the amount and type of heparin to be neutralised, its route of administration and the time elapsed since it was last given, since heparin is continuously being excreted. No more than 50mg of protamine sulfate should be given in any one dose. Prosulf should be administered by slow intravenous injection over a period of about 10 minutes.

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